The effect of alternate-day feeding on growth and feed conversion in Atlantic cod Gadus morhua

This study aimed to investigate the effect of alternating feeding (Alt) compared with control being fed every day (Con) in the on-growth face of Atlantic cod. Individually marked fish (198 and 98 in the Con and Alt groups, respectively) was sampled for weight and length on 6 occasions over a 15-month period, where mean weight increased from 628 and 758 g to 2635 and 3041 g, for the Con and Alt groups, respectively. Feeding alternate day resulted in 13 percentage more weight gain in the alternating feeding group (2283 vs. 2007 g) and improved feed conversion ratio (FCR, 1.07) compared with control (FCR 1.45). The Alt group consumed significantly less feed (27%) compared with control. The results demonstrate that feeding costs can be drastically reduced without compromising biomass growth by using feeding on alternate days during the on-growing period of Atlantic cod.publishedVersio

The importance of exercise : Increased water velocity improves growth of Atlantic salmon in closed cages

There is increasing concern about Norwegian salmon farming and the possible environmental impacts from sea lice, escaped fish and release of toxic chemicals and organic emissions to the coastal waters. Closed containment systems (CCS) have the potential to eliminate the problems with sea lice and to reduce escapes and emissions. When closing the cages, water volumes and velocity are regulated and the identification of optimal current velocities for growth and fish welfare from sea transfer to harvest size becomes necessary. This study describes two trials with LOW (0.10–0.27 BL/s) and MODERATE (0.36–0.63 BL/s) water velocity on performance of post-smolt Atlantic salmon in CCS. In trial 1 (168 days, 10.9 °C, fish size: 884–3007 g and 41.5–59.0 cm), round weight increased with 219 g (p = .012) and condition factor with 0.11 (p = .016) in the MODERATE group compared with LOW group. The MODERATE group obtained specific growth rate (SGR) of 0.76 and thermal growth coefficient (TGC) of 2.75, compared to 0.72 and 2.56 in the LOW group. MODERATE water velocity was also associated with higher relative heart size (RHS) (p = .016), higher liver index (HSI) (p = .005), increased fillet yield (p ≤ .001) and lower levels of cathepsin activity in muscle tissue. In trial 2 (46 days, 7.1 °C, fish size: 327–482 g and 29.9–33.7 cm), round weight increased with 52 g (p = .019) and condition factor with 0.05 (p = .009) in the MODERATE group compared with LOW group. The MODERATE group obtained SGR of 0.77 and TGC of 2.68, compared to SGR of 0.60 and TGC of 2.02 in the LOW group. No significant difference was observed in white muscle cell hyperplasia, measured as the proportion of small (< 20 μm diameter) muscle fibres (p = .145). Both trials showed only minor differences in slaughter yield, fillet quality (protein, fat, water) and mortality. The present study shows that moderate water velocity (0.36–0.63 BL/s) is favourable for growth rates for Atlantic salmon during the entire on-growing period in CCS. Effects on a broader range of metabolic variables and welfare indicators were also documented.publishedVersionPaid Open Acces

Dietary micronutrient composition affects fillet texture and muscle cell size in Atlantic salmon (Salmo salar)

During the past 20 years, plant ingredients have taken over as the main constituents in feed for Atlantic salmon. This has changed the nutrient composition of the feeds, the bioavailability of nutrients and perhaps nutrient metabolism. Plant‐based diets also contain more anti‐nutrients. The EU‐funded project ARRAINA re‐evaluated recommendations for micronutrient supplementation to Atlantic salmon feeds, and the present study compared a diet supplemented with micronutrients according to NRC (2011) (control diet, 100% NP (nutrient package)) with a diet supplemented according to the new recommendations (New NP). Tissue concentrations of pyridoxine, pantothenic acid, niacin, vitamin C, Zn and Se were significantly higher; and Cu was lower in Atlantic salmon fed the diet with the New NP compared to the control fish. The New NP also gave a near significant effect on growth, decreased muscle firmness and increased muscle cell size, and it affected metabolism of nitrogen‐containing metabolites in the muscle. While we cannot be certain which micronutrient(s) gave these effects, the B vitamins are probable candidates, since they are mediators of intermediary metabolism and have been shown to influence some of the affected metabolites

Validation of optimal levels of micronutrients in feed for Atlantic salmon

12.11.20 Feil filnavn. ellers klar for publisering. klb Source at http://hdl.handle.net/11250/2565091ASSESSFEED er et prosjekt utgått fra EU-prosjektet ARRAINA, med målsetning å validere nye anbefalinger for tilsetning av mikronæringsstoffer, særlig vannløselige vitaminer, i laksefôr. Det ble kjørt et fôingsforsøk der kontrollfôret (100 % NP) ble tilsatt mikronæringsstoffer iht. anbefalinger gitt i NRC (2011), som i stor grad bygger på forsøk med yngel av regnbueørret fra 1980-90-tallet. Forsøksfôret (Ny NP) bygget på resultatene fra ARRAINA. Det var også et kommersielt kontrollfôr (Biomar). Det var ingen signifikant effekt på vekst, men en tendens til større biomassevekst i fisk gitt Ny NP. Opptak av vitaminer og mineraler i fisken fulgte stort sett samme mønster i ASSESSFEED som i ARRAINA, noe som styrker konklusjonene når det gjelder behov fra ARRAINA. Muskelen i fisken som fikk ny NP var bløtere og hadde større celler enn i fisken som fikk 100 % NP. Denne effekten på filetkvalitet ble tolket som økt muskelcelle hypertrofi og falt sammen med endringer i muskelens innhold av noen frie aminosyrer og nitrogen-metabolitter. Noen av disse endringene er kjent som tegn på B-vitaminmangel hos mammalier.ASSESSFEED is a project with basis in the EU-funded project ARRAINA, where the aim was to validate new recommendations for supplementation of diets for Atlantic salmon with micronutrients, especially water-soluble vitamins. A feeding trial was conducted, where the control feed (100% NP) contained micronutrients according to NRC (2011) which is largely based on trials with rainbow trout from the 1980-90ies. The experimental diet (Ny NP) was based on the results from ARRAINA. A commercial control diet was also included (Biomar). There was no significant effect on growth, but a tendency of increased biomass growth with the new NP. Uptake of vitamins and minerals in the fish largely followed the results from ARRAINA, strengthening the ARRAINA requirement estimations. The muscle in fish given Ny NP was softer and had larger cells than the muscle of fish given 100% NP. The effect on fillet quality was interpreted as increased muscle cell hyprtrophy and coincided with changes in concentrations of some free amino acids and nitrogen metabolites. Some of these changes are known as indicators of vitamin B-deficiency in mammals

Validation of optimal levels of micronutrients in feed for Atlantic salmon

ASSESSFEED er et prosjekt utgått fra EU-prosjektet ARRAINA, med målsetning å validere nye anbefalinger for tilsetning av mikronæringsstoffer, særlig vannløselige vitaminer, i laksefôr. Det ble kjørt et fôingsforsøk der kontrollfôret (100 % NP) ble tilsatt mikronæringsstoffer iht. anbefalinger gitt i NRC (2011), som i stor grad bygger på forsøk med yngel av regnbueørret fra 1980-90-tallet. Forsøksfôret (Ny NP) bygget på resultatene fra ARRAINA. Det var også et kommersielt kontrollfôr (Biomar). Det var ingen signifikant effekt på vekst, men en tendens til større biomassevekst i fisk gitt Ny NP. Opptak av vitaminer og mineraler i fisken fulgte stort sett samme mønster i ASSESSFEED som i ARRAINA, noe som styrker konklusjonene når det gjelder behov fra ARRAINA. Muskelen i fisken som fikk ny NP var bløtere og hadde større celler enn i fisken som fikk 100 % NP. Denne effekten på filetkvalitet ble tolket som økt muskelcelle hypertrofi og falt sammen med endringer i muskelens innhold av noen frie aminosyrer og nitrogen-metabolitter. Noen av disse endringene er kjent som tegn på B-vitaminmangel hos mammalier.publishedVersio

The effect of alternate-day feeding on growth and feed conversion in Atlantic cod Gadus morhua

This study aimed to investigate the effect of alternating feeding (Alt) compared with control being fed every day (Con) in the on-growth face of Atlantic cod. Individually marked fish (198 and 98 in the Con and Alt groups, respectively) was sampled for weight and length on 6 occasions over a 15-month period, where mean weight increased from 628 and 758 g to 2635 and 3041 g, for the Con and Alt groups, respectively. Feeding alternate day resulted in 13 percentage more weight gain in the alternating feeding group (2283 vs. 2007 g) and improved feed conversion ratio (FCR, 1.07) compared with control (FCR 1.45). The Alt group consumed significantly less feed (27%) compared with control. The results demonstrate that feeding costs can be drastically reduced without compromising biomass growth by using feeding on alternate days during the on-growing period of Atlantic cod

The concept map as a substitute for lectures: Effects on student performance and mental health

AbstractIn comparison with traditional lectures, active learning methods have the potential to foster learner agency and consequently raise academic performance. However, these methods are often applied with little knowledge about their effectiveness. In this study, we introduced two concept maps in an undergraduate cell biology course, to investigate their effect on student performance, but also mental health, in a quasi-experimental setup. By implementing group tasks into the work, we aimed to reduce feelings of loneliness among the participants, a common phenomenon among students in the study country. We evaluated the effects of the concept maps via exam grades and in an anonymous student survey. Here, we found no increase in student performance after introduction of the active learning task. Students also did not report improvements in their feelings of loneliness. We conclude that this active learning method did not detectably improve student performance or mental health, a result which does not conform to the popular perception of positive effects from active learning. The survey revealed that students do not have a preference for either active learning or traditional lectures, however, the students experienced that the concept map helped them to describe, explain and hypothesize about the topics. Overall, this shows that the concept map method is a valid alternative to traditional lectures, since students perform equally between both learning approaches